Dipti Prasad Mishra

Numerical Analysis of Mixed Convection through an Internally Finned Tube

Wall temperature of an internally finned tube has been computed numerically for different fin number, height, and shape by solving conservation equations of mass, momentum, and energy using Fluent 12.1 for a steady and laminar flow of fluid inside a tube under mixed flow condition. It has been found that there exists an optimum number for fins to keep the pipe wall temperature at a minimum. The fin height has an optimum value beyond which the wall temperature becomes insensitive to fin height. For a horizontal tube, under mixed flow condition, it is seen that the upper surface has higher average temperature than the lower surface. The impact of fin shape on the heat transfer rate shows that wall temperature is least for triangular-shaped fins, compared to rectangular- and T-shaped fins. In addition to the thermal characteristics, the pressure drop caused due to the presence of fins has also been studied.

Effect of fin and tube configuration on heat transfer of an internally finned tube

Purpose – The purpose of this paper is to determine the heat transfer and fluid flow characteristics of an internally finned tube for different flow conditions. Design/methodology/approach – Numerical investigation have been performed by solving the conservation equations of mass, momentum, energy with two equation-based k-eps model to determine the wall temperature, outlet temperature and Nusselt number of an internally finned tube. Findings – It has been found from the numerically investigation that there exists an optimum fin height and fin number for maximum heat transfer. It was also found that the heat transfer in T-shaped fin was highest compared to other shape. The saw type fins had a higher heat transfer rate compared to the plane rectangular fins having same surface area and the heat transfer rate was increasing with teeth number. Keeping the surface area constant, the shape of the duct was changed from cylindrical to other shape and it was found that the heat transfer was highest for frustum sh...

Maximum air entrainment into a mixing pipe through optimum design

Numerical simulation of air entrainment into a mixing pipe has been performed by solving the equations of conservation of mass, momentum and energy along with a two-equation-based k–ϵ model. It was found that there exists an optimum shape of the mixing pipe (both for non-isothermal and isothermal flow condition) for maximum air entrainment into the pipe. It was also found from the numerical experiments that there exists an optimum length of the mixing pipe, both in forward and reverse direction, with respect to the position of the exit of the nozzle that can entrain maximum air into the pipe. There also exists optimum diameter of the mixing pipe and optimum distance of the nozzle from the entrance of the mixing pipe (irrespective of the different Reynolds number based on nozzle) that entrains maximum air into the pipe. For same Reynolds number, the cylindrical mixing pipe has interestingly a much shorter entrance length compared to a simple pipe. An optimum nozzle diameter could be decided by considering the mixing pipe entrainment rate and the back pressure developed by the nozzle.

Numerical Analysis of Natural Convective Heat Transfer over a Vertical Cylinder Using External Fins

The present numerical study deals with the natural convection heat transfer on the surface of a vertical cylinder with external longitudinal fins. The aim of the study was to determine the effects of geometric parameters like fin height, fin number and fin shape on the heat transfer and thus obtain the optimum parameters that will maximize the rate of heat transfer have been discussed. The numerical investigation consists of an aluminium cylinder of length 1m and diameter 0.07m with air as the working fluid. It has been seen from the numerical investigation that the heat transfer increases with fin height. It is also observed that there exists optimum fin number for maximum heat transfer. Keeping the fin number, fin height and volume fixed, it was found that the heat transfer is maximum for rectangular shaped fin.

Numerical Investigation of Fluid Flow and Heat Transfer in Finned Micro-Channels with Nanofluids

Conservation equations of mass, momentum and energy have been solved using Fluent 14 to compute the Nusselt number and wall temperature of a finned rectangular Micro-channel for a laminar flow for water and nanofluids under mixed flow condition. Alumina based water is considered as nano fluid for the present investigation. It has been found from the numerical investigation that as the percentage of alumina is increased in the base fluid (water) the heat transfer rate is increased. It has been found that the wall temperature decreases with increase in fin number. The heat transfer is found to be more in rectangular shaped fin compared to any other shape both for the water and nanofluid. In addition to thermal characteristics, the variation of pressure drop for different fin number has also been investigated.